New Standard Will Cut EV Charging Time

The Society of Automotive Engineers (SAE) approved a revised standard last week that will let electrified vehicles charge their batteries much quicker -- in as little as 10 minutes for plug-in hybrids or 20 minutes for battery-electric cars. The standard brings new technology to public charging stations and parking garages, but not to homes.

"Before, it was a matter of hours to charge an electric vehicle battery," Andrew Smart, director of SAE International, told us. "Now it will be a matter of minutes."

The J1772 standard calls for so-called DC fast charging, using voltages ranging from 200V to 500V and currents of up to 200A. Earlier versions described methods using voltages of 120V or 240V and currents of 15A or 80A. Using the new technology, plug-in hybrids will be able to go from 0 percent to 80 percent charge in 10 minutes; battery-electrics could go from 20 percent to 80 percent in 20 minutes.

GM's Spark EV could be the first to employ the new DC fast charging standard.(Source: GM)

The standard calls for connectors and electrical interfaces with two extra pins on board. Electric vehicles and plug-in hybrids already on the road, such as the Chevy Volt, will not be able to use the new technology immediately, since they don't have the new hardware and software. However, Kevin Kelly, a spokesman for General Motors, told us its forthcoming Spark battery-electric vehicle will have the new connector, interface, and software. "It's less important to do this on the Chevy Volt, because the Volt already has extended range on board," he said. "But it makes a lot of sense for the Spark EV."

The J1772 standard was created in 1996. It was revised in 2001 for use with a paddle-type connector and again in 2010 with a continued focus on AC charging. The new version is the first to address DC fast charging and the first to describe voltages as high as 500V and currents as much as 200A.

The standard reflects a consensus of 190 global experts representing makers of automobiles and charging equipment, as well as utilities, national labs, and municipalities. The experts had to consider the effects of temperature, humidity, and moisture, as well as mechanical aspects.

"You have people who are constantly plugging and unplugging it," Smart said. "You need to know everything, including the fatigue levels of the wires, connectors, and plastics. You also need to get input from people on the infrastructure side -- you've got people who write building codes, and you've got municipalities. It's not just the automakers."

Automakers say the technology could have a profound effect on the sale of pure electric vehicles, many of which require eight or more hours of charging. "This is a standard that everyone was waiting for," Smart said. "Everyone wanted it to be done quickly. But when it comes to developing a consensus between 190 technical specialists, it takes time."

Nice story, Chuck. It's amazing that the change in a standard would have that big an effect on charging hybrids and EVs. Makes you wonder why it took so long, especially on a feature that has such impact on hybrid and EV owners. This standard means you could actually take a trip with an EV.

Definitely an important development and I, too, wonder what took so long. But then again, everything seems to take long in this segment of the market.

Also confusing to me is why does this have impact on commercial and public charging stations, but not for home use? Is it something to do with the voltage and residential infrastructure. Seems to me they'd want to address that.

Beth, I think that the issue with using this standard for home use is the current draw. Typical service to a home is 200A. This would use as much. I guess if you were willing to turn off everything in your home then you could use it. It is not only what is in your home that matters, but the infrastructure serving it. This would require a big upgrade in that. Commercial locations will have new infrastructure, thus will be able to deal with the current draw.

Most home service is 240V at 200A. The indication above is that you use 500V at up to 200A. This is about twice the pwer that is available at a typical home for everything. You would have to resort to a storage system to provide the current for your car at this rate for the shorter time period.

I guess the lesson in all this, is that progress moves in fits in starts - but it has to start somewhere. The market will ultimately decide what is a "livable" solution, once the standards wars have died down.

Beth, my guess is right about the voltage in the home. I think the important part of this development is that it could free the EV to travel beyond short trips from the home. Waiting 10 or 20 minutes at a public charging station is not that inconvenient.

Most homes have single-phase AC, Beth, which won't cut it for fast charging. Fast charging requires three-phase AC (and the associated higher voltages and currents), which is typically used in industrial applications today. In contrast, today's home-charging systems usually use single-phase AC at 120V and 15A (about 16 hours or less) or single-phase AC at 240V and 15A (about 8 hours or less). SAE's new standard calls for up to 200A and up to 500V. Making those modifications to a home would be very expensive.

Of course you mean most homes in North America, not France, for example. In any case, a home either has a 24 kVA or 48 kVA power entry. A full charge is perhaps 16 kWh. The math says 20 minutes but likely more if you want to keep the lights on or less if you have storage. But everything has to start somewhere. Setting the vehicle capability high in a standardized way permits standards to be developed. 10 minute charging implies 96 kVA at the vehicle and ~10 kWh of storage in a residential charger. Or, houses could be supplied with 240/120 3-phase (wild phase) power, like many commercial buildings, increasing the service to 83 kVA for the cost of one wire. But in the real world, most people don't drive around running on empty. Nor is their average time parked in the drive less than 30 minutes. Obviously for PHEVs - you get what you get based on time available but full charge is only 4-10 kWh so 10 minute charge at home may just be doable.

A standards war is almost inevitable at this point. On one side we have CHAdeMO (up to 500VDC at up to 125A), which uses its own (large) connector and signalling is done using CANbus. On the other side we have the new J1772-DC standard (200-450VDC at up to 200A), which employs one of the most hideous connectors I've ever seen, and uses homeplug power line carrier for signalling. (The original J1772 scheme, which the new one also supports, did its signalling by varying the duty cycle of a 1 Khz square wave.) And then there's Tesla, which has their own fast DC charging scheme, using a much smaller very sleek connector employing who-knows-what type of signalling.

A fair number of cars already have CHAdeMO support. And the State of California is reportedly in the process of installing around 200 CHAdeMO chargers. Tesla is rolling out superchargers in various places.

It may be possible to build adaptors - the Tesla Model S comes with a J1772 adaptor that works reasonably well in my limited (1 month) experience. But building an adator that handles 90Kw isn't exactly trivial even if you're able to run the DC through it directly, which is by no means certain to be possible in all cases.

Speaking as a veteran of the IETF/ITU standards war, I can't say I'm looking forward to another one.

I was wondering the same thing. Why on earth wouldn't the SAE just adopt the existing ChaDeMo standard that has existed for many years, and is already installed on thousands of vehicles worldwide? Okay, so now we have a standard. What do we need to do to get chargers installed in useable spaces nationwide? can we get SAE chargers in rest areas along interstates? What about shopping centers? National parks? How about at dealerships that sell EV's (and leave the dang things "ON" after hours)? Let's move this along now!

I asked the same question about why it took so long, Rob. Their answer is a logical one. Getting a consensus of 190 technical specialists is difficult. That reason apparently didn't stop the ChaDeMo standard, however.

At the Siemens conferece, I heard of another solution to help EVs travel farther than short trips -- battery swaps. You pull into a station and they take your battery and replace it with a charged one. Apparently this is more common outside the U.S.

A Better Place, a company formed by ex-SAP exec Shai Agassi, is one of the more prominent companies pursuing the battery swap model. They are pilot testing their changing station network in Israel and have plans to expand in Europe and China, but I don't believe the U.S. is on board quite yet.

That's a great point, Rob. What if you purchase a vehicle that by its class and cost, has a more robust (i.e., more expensive battery) in play or even just a newer version of the standard battery used by all the participants in the swapping network. I wouldn't want to trade up my high-ticket battery for anything sub-standard.

In the Better Place, scenario, people don't actually own the batteries, they take part in a network where the batteries are swapped out and consumers simply pay for energy they use. I think the network is also built to accomodate a specific car model, although I'm not entirely sure on that point. Seems like there is still a lot to be worked out before it could become a truly supportable model.

one approach for swapping that might work would be for cars to be equipped for two batteries - one that comes with the car and space for another one that is there for swapping networks. It could also then work for those who could leave one battery at home charging during the day and use two only when going on a long trip. These are heavy and you could save by carting around only half the battery capacity when you don't need more. This might work if each battery gives about 100 miles or so of driving capcaity. Are we there yet?

@kellerbl: I like that idea. So the swapping or second battery could be more of standard commodity so there's no worry about features/functions/condition. The primary battery could then be the platform for EV maker differentiation.

Thanks Beth. Of course larger vehicles may have room for multiple secondary batteries for swapping. I can also imagine a trunk design that could allow more secondary batteries to be loaded at the loss of cargo space, assuming weight balancing could be accommodated. If the swappable battery's cost was $2K or less, I could imagin people buying a couple to swap at home and charge whenever they get the best rate. This also helps to deal with the issue of coming home to park and not having enough KWh left to go somewhere (perhaps an emergency trip). It would be nice to have that spare battery you could swap in if you needed to go somewhere on short notice.

However, there are still safety issues and external power input needs that would need to be resolved. And cars like the Leaf are not rated for towing, though that could probably be amended if the battery trailers could weigh within 500 lbs or so.

I agree the ebuggy, while neat, has its own set of challenges. And that fast charging for 30 minutes or less is more practical than battery swapping. Could they even work that to less than 30 minutes? That could change, but so will battery chemistries.

...these programs seem to be the only solution to help EVs go beyond their limited range.

P.S. If you can't afford a Tesla S and your driving needs require more than 50 miles one way, or thereabouts, a pure EV is probably not your solution today. That's why there are plug-in hybrids here and coming, which allow pure EV mode for much of our shorter trips. As Volt drivers have proven, real world gasoline use is drastically reduced even with a pure EV range of only 35 miles.

Also, if Envia's promises prove reasonably true, I suspect that competitor cell manufacturers will very soon find comparable performance by different but similar means. Alternately this technology could be licensed. So this could be big enough until the next "perfect battery" is realized practically.

1) You are swapping out a very expensive part of the vehicle, and they degrade. Would you be happy swapping out your brand new $10,000 battery for one with half the capacity? On the other hand, if your mechanic told you you'd need a new $10,000 battery in a few months, would you pay it if your alternative would be to just 'swap it out' for $50 and saddle someone else with the replacement costs?

2) Batteries are physically big and heavy. Many city gas stations won't want to pay for the real estate/storage facilities required.

3) Batteries are hard to change. The Leaf battery weighs almost 700 pounds, and the machinery/fixturing to handle that kind of weight is not simple or cheap.

4) Li-ion batteries do not last long if stored fully charged, so you'd reduce the overall life of the pack by storing fully charged batteries. (And if you're not storing them fully charged you lose most of the usefulness of the battery swap station.)

Billvon, Every one of your reasons why battery swapping won't work has merit. Your comment lays out why this concept will likely not work. Quick charging seems to be the likely solution to letting EVs off the leash.

I also am amazed at the length of time to develop (or publish) the standard. Looks to me like the automotive industry would begin with a viable standard and design around that or at least plan on their product being tested to it. I am not in the automotive industry so I don't really know the ins and outs of the industry but it does seem strange.

At a conference last week, I spoke with a design engineer from Lear. He is involved in crafting drive chains. He said the standard does not affect how the car is designed. It only affects how the car gets charged up.

At least this coal burning is domestically made energy rather than part of the $37 Billion we send each month to foreign countries that want to kill us. The implementation of EVs and PHEVs could have profound impacts on our debt while creating thousands of new jobs in the energy production and distribution related fields.

You don't have to burn any coal. No one is holding a gun to your head. It's a concious decision on your part to do so. Each and every individual American uses 3.4 tons of coal each year. Good choice. There are plenty of better energy sources. The only excuse for coal is that it's cheap mostly because they are exempt from environmental regulations which everyone else must meet and because no one put a value on the land use (now over 200 mountains and 15000 miles of waterways obliterated). At the current rate, in your lifetime you personally will have destroyed 2.5 acres of land and along with 250 friends killed one human. Nice one.

Good question, Lardo140. I'll try to get an answer for you (or maybe one of our readers knows the answer). The last 20% takes a long time because the charge rate slows down at that point. Because these battery packs are so expensive, everyone is afraid of damaging them through overcharging.

10 minutes get's us to 80% charged. How long will it take to get to 100%?

You typically would not fast charge past 80%. You'd revert to Level 1 or 2, as it is then approaching the top-off region. At level 2 that would typically add about 24 miles of range per hour for a 6.6kW on-board charger.

CharlesM; Recently I have met people involved with electric transit buses. And they prefer to discharge no more than to 30%, and not charge to more than 80%. Past this range the lifetime of some battery chemistries is shortened. They prefer a sodium nickel chloride battery since it is less sensitive to charging cycles, with an operating temperature of about 300C.

...they prefer to discharge no more than to 30%, and not charge to more than 80%.

That's the principle with the Volt's pack, and I and many other LEAF drivers try to do that with our cars too. I even try to do that with all my lithium portable devices. Downside is that you're paying for and lugging around twice the battery you use. Anyway, the CHAdeMO fast chargers (eg, Blink) do not allow fast charging past 80%.

BTW, many in the LEAF community believe there was a large lobbying effort toward this new SAE standard largely to orphan manufacturers like Nissan that had already settled on an incompatible standard.

So, I'm not an Engineer, so, this may be an incredibly ignorant question, but, from a consumer (who is *extremely* interested in getting an electric car) standpoint I wonder about compatibility. The article mentions that the quick charging stations won't be available for homes (which is fine), but also mentions that the hardware will have two extra pins... will the interfaces still be able to be used with home-based charging stations?

The interesting thing about the whole standard is that there is no mention of how the heat generated during charging will be handled, nor any indication of how the battery technology will change to handle the massive amount of energy dumped into the battery so very rapidly. WE could supply a thousand amp charger and probably melt most of the current batteries during a two minute "really fast charge". My point is that no mention has been made about the other end of the charging string-the battery. That is a serious issue that could use a bit of discussion.

Keep in mind that this is not a battery pack design, or a battery pack controller - it is just the charger side of things. The battery pack is responsible for its own thermal management. The battery pack can request as much (or as little) power as it wants, so no risk of having a high power charger damage a small/low power battery.

Battery swaping is a stupid dream for all of the reasons already given, and also because of the skill needed to do it. Not only the electrical connections, but also the mechanical attachments will certainly stump a whole large segment of the population, with a lot of failures resulting.

And, once again, there has been no real consideration of the battery side of the much higher recharge rate. Could you even drive away in a car whose battery was already at the upper temperature limit, or even higher? How much battery life would be lost in such a charge? What about connector melt-down"? In the industrial world, where reliability matters a bit, the high current connectors used are fairly expensive, and they require a bit of skill to use and replace. There is the very real chance that a damaged fast charge connector would continue to be used and damage the connectors on the next few vehicles being charged.

As for the connector standards, and then the commuynication standards, we are probably likely to see a situation more like we have with computers, where the goal seems to be that each application uses a connector unlike any other in existance. This is done to assure a captive market for replacements.

So the result will probably be that charging stations will need to deal with many different interfaces, even if some allegedly universal standard is created. The resulting confusion will probably do more to damage the reputation of electric vehicles than any other problems would. It will be interesting indeed to see if there is any way that it could be made to work. The one way that I can see is for the charger to be part of the vehicle and the connector be for the AC power input, which would utilize current industrial standards for connectors and the actual connections.

A few weeks ago, Ford Motor Co. quietly announced that it was rolling out a new wrinkle to the powerful safety feature called stability control, adding even more lifesaving potential to a technology that has already been very successful.

It won't be too much longer and hardware design, as we used to know it, will be remembered alongside the slide rule and the Karnaugh map. You will need to move beyond those familiar bits and bytes into the new world of software centric design.

People who want to take advantage of solar energy in their homes no longer need to install a bolt-on solar-panel system atop their houses -- they can integrate solar-energy-harvesting shingles directing into an existing or new roof instead.

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